The invention is related to the area of cancer genetics. In particular it is related to somatic mutations associated with cancer.
The human mitochondrial genome is a 16 kilobase circular, double stranded DNA that encodes 13 polypeptides of the mitochondrial respiratory chain, 22 transfer RNAs, and two ribosomal RNAs required for protein synthesis. The mitochondrial genome is particularly susceptible to mutations because of the high level of reactive oxygen species generated in the organelle coupled with a low level of DNA repair (7-10). Surprisingly, there has been little detailed analysis of alterations in human mitochondrial DNA in cancer, although there are indications that mitochondria may be involved in neoplasia and apoptosis (2-6) as well as cancerous growth (1). Thus, there remains a need in the art to identify a correlation of alterations in human mitochondrial DNA with cancer.
It is an object of the invention to provide a method to aid in detecting the presence of tumor cells in a patient. This and other objects of the invention are provided by one or more of the embodiments described below.
One embodiment of the invention provides a method of screening patients for the presence of tumor cells. The method comprises a step for determining the presence of a single basepair mutation in a mitochondrial genome of a cell sample of a patient. If a single basepair substitution is found in a cell sample of the patient which is not in normal tissue of the patient, the patient is identified as having a tumor.
The invention thus provides the art with new methods of detecting and tracing tumors by examining mitochondrial DNA for the appearance of somatic mutations.